The present invention relates to awning window hinges and in particular to a sliding shoe used in awning window hinges, the shoe providing adjustable clearance and friction in its engagement with a hinge track.
Awning window hinges provide for the pivotal opening of a window about a horizontal axis through the use of left and right awning window hinges supporting the window sash. A separate operator opens and closes the window, typically through the use of a crank mechanism. The awning window hinges are in the form of a two bar linkage, the first bar being a sash arm attached along the window sash and having one end pivotably attached to one end of a guide arm forming a second bar of the linkage. A remaining end of the guide arm is pivotably attached to a track extending along the window frame. The remaining end of the sash arm is pivotably attached to a shoe sliding along the track.
With this hinge mechanism, the pivot point of the window moves with the shoe as the window opens preventing interference between the window and the window frame.
The shoe is typically held captive on the sliding track by a channel running along a shoe support surface of the track. A ridge of the shoe fits within this channel. The shoe must have sufficient clearance in its fitting with the channel to slide along the channel as the window opens but must not have so much clearance as to wedge within the channel or "chatter" in its movement. A certain degree of friction between the shoe and the channel is also required to stabilize the open window against the forces gravity and the force of wind catching the open window.
The shoe support surface of the track is typically vertical and the channel perpendicular to the shoe support surface to open the shoe support surface. The rail of the shoe, which engages the channel, is therefore generally perpendicular to a shoe plate engaging the shoe support surface of the track. It is known in the prior art to separate the rail from the shoe plate near the center of the shoe and to place in that separation a wedge (typically a screw) producing a bulge at the middle of the rail causing the rail to fit more tightly within the channel. Adjustment of the screw allows adjustment of the fit between the rail and the channel.
The shoe must be constructed of a sturdy material and is typically manufactured of a formed steel sheet surrounded by an injection molded plastic matrix. Accordingly deformation of the rail requires considerable force and adjustment of the shoe is relatively difficult. Further, the adjustment screw tends to be located underneath the sash of the window making it necessary to disconnect the operator from the hinge for adjustment to take place.